Differences Between In-Vivo Flushing and OPU-ICSI
When it comes to maximizing the reproductive success of your mares, choosing the right technique is crucial. This page explains the main differences between In-Vivo Flushing (uterine lavage) and OPU-ICSI, helping you make an informed decision.
HOW DO THE TWO TECHNIQUES WORK?
In-Vivo Flushing (Uterine Lavage)
This is the traditional technique often incorrectly referred to as Embryo Transfer, which is actually just one step in the procedure, also present in other assisted reproduction techniques (ART). The key aspect of Flushing lies in the uterine lavage of the donor mare to retrieve the embryo.
Procedure:
Fertilization occurs directly in the donor’s reproductive tract via natural or artificial insemination. After 7-9 days, the embryo is retrieved through uterine lavage and transferred to a recipient mare.
Characteristics:
- Adatta solo a cavalle fertili.
- Richiede un’attenta sincronizzazione tra donatrice e ricevente.
- Possibile solo durante la stagione riproduttiva.
- Può interferire con il programma sportivo della donatrice.
OPU-ICSI (Ovum Pick Up and ICSI)
This is the most innovative technique, widely used in humans for decades, offering an advanced solution to tackle reproductive challenges with flexibility and superior results. OPU-ICSI is the result of years of technological development and represents a breakthrough in equine reproduction.
Procedure:
Oocytes are retrieved from the donor’s ovaries using the Ovum Pick Up (OPU) technique, which involves the use of an endovaginal ultrasound probe to visualize ovarian follicles and collect oocytes. In the laboratory, each oocyte is fertilized with a single sperm cell through Intracytoplasmic Sperm Injection (ICSI). The resulting embryos can be frozen and transferred at the breeder’s most convenient time.
Characteristics:
- Suitable even for less fertile or sterile mares.
- Can be performed at any time of the year, without seasonal constraints.
- Allows for a higher number of embryos per single procedure.
COMPARISON BETWEEN FLUSHING AND OPU-ICSI
Flushing: On average, two Flushing cycles are needed to collect a single embryo.
OPU-ICSI: Each OPU procedure yields an average of two embryos.
Flushing: Limited to mares with good fertility. Only fertile mares benefit from this procedure, making it less suitable for mares with reduced fertility or advanced age.
OPU-ICSI: Suitable for mares with low fertility, advanced age, or sterility, offering a solution when other techniques fail or are not recommended.
Flushing: Limited: Restricted to the mare’s reproductive season, allowing embryo collection only at specific times of the year.
OPU-ICSI: Unlimited: Can be performed year-round, regardless of the reproductive season, offering greater planning flexibility.
Flushing: High: Requires a large amount of semen, up to three straws per cycle, which can be costly, especially with rare or high-value semen.
OPU-ICSI: Optimized: Requires only a minimal amount of semen, using a small portion of a single straw. This preserves genetic material and allows the use of rare or limited semen.
Flushing: Difficult: Post-Flushing freezing is complex and rarely used, limiting storage options and future transfer opportunities. Fresh embryo transfer is usually preferred.
OPU-ICSI: Easy: Embryos can be safely stored for over 10 years, offering greater flexibility for future use.
Flushing: Minimal: Requires precise synchronization between donor and recipient, reducing flexibility in the transfer process.
OPU-ICSI: Maximum: Oocyte retrieval can be performed on a day-hospital basis, and embryo transfer can be scheduled at the breeder’s convenience.
Flushing: Complex or Late: While technically possible, pre-implantation sexing is invasive and poses risks to the embryo. It is usually performed post-implantation via ultrasound when pregnancy is about 60 days.
OPU-ICSI: Early and Safe: Can be performed pre-implantation directly in the lab through targeted analysis, allowing the selection of embryos for implantation while preserving their quality.
Flushing: Frequent: Requires frequent monitoring to pinpoint ovulation, increasing costs and time required for the procedure.
OPU-ICSI: Single: Requires only one monitoring session before OPU, reducing time and stress for the mare.
Flushing: Pharmacological: Often requires hormonal treatments to synchronize the recipient with the donor, increasing complexity and costs.
OPU-ICSI: Minimal: Utilizes the recipient’s natural cycle, avoiding pharmacological treatments and improving animal welfare.
Flushing: Unpredictable: Difficult to estimate due to the low success rate and frequent monitoring, which increase costs.
OPU-ICSI: Transparent: Costs are predictable, based on a clear price list for each phase (OPU, ICSI, Embryo), providing greater financial clarity and reliability for the breeder.
| IN-VIVO FLUSHING | OPU-ICSI | |
| EMBRYO PRODUCTION RATE | 0.5 per flushing | 2 per OPU |
| MARE FERTILITY | Limited: Only for fertile mares | Extended: Also for older, less fertile, or sterile mares |
| SEASONALITY | Restricted: Only during the breeding season | Unlimited: Any time of the year |
| SEMEN QUANTITY | High: Up to 3 straws per cycle | Optimized: Small portion of a single straw |
| EMBRYO FREEZING | Difficult: Unreliable | Easy and harmless for the embryo: can be stored for over 10 years |
| FLEXIBILITY | Minimal: Donor-recipient synchronization required | Maximum: OPU performed as day-hospital and embryo implanted when most convenient |
| SEXING | Invasive and risky: an invasive procedure on the embryo | Safe via targeted lab analysis, harmless to the embryo |
| DONOR MONITORING | Frequent to identify the follicle | Single, before OPU |
| RECIPIENT MONITORING | Pharmacological: Synchronization with donor | Minimal: Utilizes natural cycle |
| COST | Unpredictable due to low success rate and frequent monitoring | Transparent and defined |
Why Choose OPU-ICSI?
OPU-ICSI is an advanced solution to maximize reproductive success, ideal for:
- Ensuring greater flexibility and optimal results in reproductive programs.
- Mares with low fertility or uterine issues.
- Situations where the available semen is rare or of limited quality.